Propane, also known as liquefied petroleum gas (LPG) or autogas, is a three carbon alkane hydrocarbon (C3H8). It is a nontoxic, odorless gas at ambient temperature and pressure. It can be stored as a liquid at moderate pressures (300 PSI) or at temperatures below -44oF. In its liquid form, the energy density of propane is 270 times greater than in its gaseous form. However, a gallon of liquid propane has approximately 25% less energy content (BTUs) than a gallon of gasoline.
Propane is a byproduct of natural gas processing and crude oil refinement, and therefore it is not a renewable energy source. Propane fuel used for vehicles must be 90% propane. Butane (C4H10) is a common minor component, as well as propylene and butylene. Commercial
propane also contains the odorant Ethyl mercaptan, which aids in leak detection.
Propane has been powering vehicles since the early- 1900’s, and is currently the world's third most common engine fuel. It is a high-energy, high octane, clean burning fuel. Propane’s nearly complete combustion reduces carbon monoxide, nitrogen oxide, hydrocarbons, particulate matter, and greenhouse gas emissions - emissions are dependent on vehicle type, drive cycle, and engine calibration. Propane is also not a greenhouse gas when released directly into the atmosphere. However, propane vapor is denser than ambient air, and will sink and pool when released. Therefore all fueling and repair should be conducted outdoors, or in a well-ventilated area, that is at least 25 feet from an ignition source
Additional benefits of propane include its low cost per gallon compared to traditional fuels, and the relatively low cost of refueling stations compared to other alternative fuels. Furthermore, over 97% of the propane consumed in the U.S is produced in North America, advancing our nation’s energy security.